Think you’re a bright one? Come on then, wreck yourself on these fiendish scenarios.

1. A Curious Café

Q: A café has two waiters: Darius and Drump. Darius gets orders right 90 percent of the time. Drump is a lunatic who serves a single poached egg no matter what the customer orders. Out of the 21,000 items on the menu, 15,000 are designated as Breakfast Specials, a list that changes each day at the discretion of the chef. However, at least two-thirds of the Breakfast Specials are always Toast Plates (that is, they consist only of various kinds of toast in different proportions), while at least one half of the Breakfast Specials have the word “soup” in their title (though none of these necessarily contain soup). Otherwise, the menu is random. If Drump can serve 16 customers in an hour, and Darius can serve one customer every seven hours, how many customers per day order soup and then actually receive soup?

Hint: The chef has no name.

A: No one ever goes to this café.

2.The Silver Key

Q: On his deathbed, your ailing father calls you close, presses a silver key into your hand, and whispers the following in your ear: “First, drop it. If nothing happens, you can taste it, but then you must burn it all. Do not under any circumstances let Shannon read it.” Why?

A: Your father was talking about the secret list of people who have wronged him, which he keeps in a box by the fireside. The box is made of wood. A clause in his will rescinded all bequeathments to anyone who had wronged him, including Shannon. The box, as you may have guessed, was flammable, but the list was printed on a volatile material that had a half chance of being flammable and a half chance of being both explosive and poisonous. On his deathbed, your father forgave Shannon and resolved to destroy the list without her ever finding out that she was on it. His instructions were the only way to do so reliably and safely.

3. The Philosopher’s Syllogism

Q: All people are mortal. Some mortals are male. Some males are depressed. Not all redheaded mortals are depressed. Some redheads are black. All redheads have red hair. All Asians are redheads. None of those who are black are both depressed and Asian. All mortals are Asian. Socrates is tired. Most, but not all, redheads are weaklings. Some tired people are depressed. Some mortals are hopelessly depressed. What follows?

A: Some Asians might or might not be depressed males.

4. 10,000 Coins

Q: I have 10,000 coins, while you have just 25 coins. I have much money, but you are poor. Now, we can see by inspection that 10,000 coins is more than 25 coins. Exactly how much more, though? Express my net worth as a percentage of your net worth. My value, in terms of yours.

Hint: Try 40,000 percent.

A: I own you. I could destroy you.